It's loosely based on the Engel VIIc interior design and works with 2 x 750 ml piston tanks, brushless motors and LiFePo batteries. The technical components are mounted into a frame made out of 5 mm milled thick glass fiber plates and M5 thread rods:

The whole assembly will be housed in glass fiber tubes sealed with bayonet coupling:

Took three tries to get the ruder and the hydroplanes right. New moulds are often a bit tricky. But now I'm quite pleased with the results. Brass shafts and glass fiber / carbon fiber blades. Rock solid.....

The front servo will be located in a smaller tube attached to front of the main pressure tube. To be able to install and remove it, I have located it on a mount, that can be pushed over two thread rods and that will be secured by two M5 nuts.

The brushless motors have watertight feedthroughs that just get mounted in the motor flange and that are secured by a M18 nut. The feedthroughs are custom made.

After a longer break, I can report progress again. The struts to hold the pressure tube are installed, the screw points for the pressure tube are in place, the drive shafts are installed and the front servo compartment is secured. Looks like a true two-hull sub.....

And again some progress. The hydroplanes and the stabilization fins are installed. The mechanics for the rear hydroplanes is somewhat complicated, as the hydroplanes are too close to the pressure tight compartment to be directly connected to the push rods and the propeller axis prohibit a straight hydroplane axis. So everything is controlled via a second axis....the connection for the rudder is installed as well:

Allot of work as well, the water inlets in the upper hull. I didn't just want to file some, so I fabricated frames from pu-resin and glued them into slits in the upper hull, filled everything and sanded it down flush to the hull's outer surface.

Similar business are the snorkel housings. Got the rapid prototyped and then glued them to the underside of the deck. After that the open parts in the deck were milled and filed away. Front: